


Swapping things up

by Amashi_zaino



Category: Fellswap - Fandom, Undertale (Video Game)
Genre: And it was HELLA FUN!, Complete, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), How Do I Tag, M/M, Multi, Oemaki, PWP, Puuuure smut, Ribbed for his pleasure XD, Short One Shot, Something for the guys, Spinoff, gayest thing I've ever written, sorta - Freeform
Language: English
Status: Completed
Published: 2018-04-12
Updated: 2018-04-12
Packaged: 2019-04-21 21:17:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,848
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14293650
Author URL: https://archiveofourown.org/users/Amashi_zaino/pseuds/Amashi_zaino
Summary: You made friends with the Fellswap bros but one night you caught 'Rus snooping in your sketch diary. There were dick pics in there! Your imaginings of what the Skelebro's might be *ahem* packing. Aaah shit...wait...what is he doing now?!





	Swapping things up

The Fellswap bros were over, Sans was busy in the kitchen but Rus was oddly absent. You noticed that the door to your room was cracked. Silently you creeped up and peaked inside, you saw Rus lying on your bed, a book in his hand...wait...that was your sketch diary! SHIT! You had written down all of the information you’d had of the AU’s and the Skels in that book, as well as the different theories of how this timeline had come about. Plus….there were some rather…*ahem* risque pictures in there of the different Sanses and Papyri that you’d drawn while bored out of your mind. 

You took in Rus’s expression, his brow bones were drawn in a frown, but when he turned the page his face exploded in a deep orange blush. Yep, he got to the porn. Shit. 

You wanted to see what he’d do with the information though so continued to watch like the dirty voyeur you were. 

Sweat beaded on his skull as he took in the images. He turned the page again and started. He looked at it, then down to his own pants then back to the picture. His teeth hitched in a grin and he looked up and around. You hid from the crack before he could see you and when you looked back you had to cover your mouth to keep the gasp from coming out. He had an orange colored pencil in his hand and was drawing in your book, the thing that made you gasp however though was the fact that his fly was open and his long AND thick length was sticking out of his pants. You watched, enraptured at the look of his magic. Saliva pooled in your mouth and you had to suppress a whimper. It’d been almost a year since you’d last gotten laid, your hand and toys only could do so much. It wasn’t anywhere near as good as the real thing, especially since the real thing was quite literally magical. 

He kept glancing at his dick before going back to sketching. You noticed that he had piercings on it, three along the underside and two along the sides of the head. Holy shit that was hot. You wanted to do...fuck, SOMETHING. But you couldn’t...could you? Would Sans forgive you if you slept with one of the other skeletons? You were starting to have your doubts that you’d ever see him again. You knew he was still alive, you could still feel the remnant of his Soul bonded to yours pulsing within you. But just because he was alive didn’t mean he’d be able to come to you. Biting your bottom lip you looked towards the living room, you could hear the clang and uproar coming from Berry and you grit your teeth. You were so lonely. You felt so empty inside, even with the Magic from your Bara skeleton mate pulsing there it was like there was a big void in your heart. You’d grieved over these past 6 or so months, you were grieving still but something inside of you snapped. You didn’t want to feel lonely any more. You needed some intimacy, Rus had been quickly becoming one of your favorite people. He was kind, soft spoken, laid back, funny and smart as hell. It didn’t hurt that he was damn good looking. Well...good looking to you. Undertale had kind of skewed your views on your definition of “sexy”, you _were_ a dirty skele-fucker after all.

 

You made your decision. And you’d deal with the consequences when and if they happened.

The look on his face and his turgid magic standing at attention from his jeans made heat pool in your abdomen while your pants became uncomfortably tight. Silently you opened the door and walked over to him, he was engrossed in his own sketch but startled as you climbed onto the bed. 

“Rus...it’s kinda rude to snoop in someone’s diary. Do I need to punish you?”

Your voice had dipped in register as you hovered over him, pinning his legs with your hands as you glanced down at the throbbing cock just beneath your throat. 

“i..i...darlin’ it’s not what it looks like.” he said lamely.

You smirked as you wrapped a hand around his dick, the feeling made him hiss in a breath as you continued looking up at him. “Oh? It looks to me like you were snooping, and maybe even getting ready to do something else?” You dipped your head down, warm breath ghosting over his member. The book was long forgotten at his side and he brought a hand to his teeth. 

“holy...fffuck…” he groaned as you flicked out your tongue to lap at his head. “th-this doesn’t seem like much of a punishment...fuck!...i musta fallen asleep...i gotta be dreamin. no way this is actually happenin’”

“Oh, it’s happening. Rus, I’ve been so lonely. And you’ve provided me with a wonderful opportunity.” you ran your tongue over his length from base to tip making his bones rattle. 

“I have a proposition for you….I’m in need of a friend with, heh, bonefits. Think you’re _up_ for the position?”

He was huffing, face burning dark orange. His eye flared with magic and his phalanges reached down to tangle into your hair. “shit...darlin. how could i turn down an offer like that.” 

You smirked as you finally took him in your mouth. His fingers tightened in your hair as you gave him a long hard suck. Your hands finished undoing his belt and pants before pulling them down roughly. “Papyrus….I’m going to ride you hard, if you want me to stop then just say Red. Ok?” 

He nodded as you nipped at his magic, running your teeth along his length. He whined at the feeling but bucked into your mouth making you grunt slightly as he reached the back of your throat. You pulled off of him to take off your own pants and boxers. Your cock stood at attention, a bead of pre slid down your length and you pumped it a few times. “Rus...can...can you make me um.” your face flushed a bit at the suggestion of asking for him to make an ass for you. But he quickly caught on and watched with fascination as his magic filled out his pelvis and slightly down his femur in an Ecto body. You couldn’t hold back a shuddering breath at the sexy sight of his magic filling him in. You leaned down again and licked up over him, going down and playing with the testicles he even made. You sucked and slurped at him, your tongue moving and tasting along his opening and reveling in the tingling pop of his magic. He groaned and twitched as you lathered him up. You pulled away to make sure you grabbed a bottle of lube just in case. You leaned in and pulled him forward by the collar around his neck. “Suck.” you whispered in demand, leading his head down towards your throbbing member. His jaw parted and a long, sticky tongue lolled out and wrapped around your cock. You moaned in appreciation at him finally touching you. His hands wrapped around the meat of your ass as he pulled you closer. Your cock moved into his mouth and you saw that he made a throat as well. The hot magic was slick and warm as it pulsed and seemed to milk you, squeezing you tightly. With a deep moan you bucked into his mouth, making him grunt and groan in response. Your hands wrapped around his skull as you fucked his mouth. 

Shit, he was good, so damn good! You could feel your balls drawing up, you were getting close but pulled away before to give your body time to cool down. 

“Nuh uh, not yet. I wanna make you cum first Rus.” 

You moved back down his body, divesting him of his hoodie and shirt so that you could have full access to his bones. You took in the dings, chips and scars along his ribs and spine. Your lips descended on him, licking and kissing every one. “You’re so fuckin sexy Rus...you have no idea how much I’ve wanted to do this with you.” you whispered as you got back to his cock. You plunged down on it, taking as much as you could in your mouth. He jolted with a shout as you stuck a lubed finger into his opening, stretching and preparing him for you. 

You could feel his magic constricting around your fingers as you worked him over. His hands were tangled again in your hair, pulling and pushing trying to get more. You sucked hard before taking him as far as you could down your throat, repressing your gag reflex. His hips bucked up as he cried out and you felt his hot release shoot down your throat. Your swallowing only lengthened his pleasure but you had to finally pull back for air, leaving him breathless. 

“darlin...that was…”

“WHAT’S GOING ON HERE?!”

Your head turned to see Raspberry standing in the door, face aflame and you got a wicked idea. But you weren’t one to mince words so just told him straight. 

“We’re having sex. What’s it look like. You can join in if you want.” 

Berry’s face turned into a bright tomato, his eyelights taking in the sight before him as you pumped Rus’ cock and rubbed it along your own. 

“I..I…”  
You pouted at him. “C’mon sansy….please….I want you too…”

You looked at him through your disheveled hair, bottom lip out in a pout. Berry’s hands clenched into fists before he stepped in and closed the door behind him. 

“YOU WANT THE MALEVOLENT SANS AS WELL? YOU’RE A VERY GREEDY BOY AREN’T YOU?”

You giggled slightly at that and gave him lidded eyes. “Yep...I’m pretty greedy. And...needy...please….please Sans. I...I want you here with us.”

Berry took his clothes off, folding them and putting them aside before climbing onto the large bed behind your kneeling form. He wrapped a hand around your throat and pulled you back into his chest. “Well Human. Than You Better Be Prepared To Be An Obedient Little Pet Or You Won’t Be Allowed To Cum. Understood?” 

You swallowed, the feeling of his hard bone squeezing around your adam's apple sent a thrill through your body. You nodded. “Yes sir.” you whispered as he pushed you down on top of his brother. 

“GOOD, NOW..I WANT TO SEE YOU FUCK HIM.” 

You blinked at the smaller skeleton before looking at Rus. his face was a burning orange, whether it was from arousal or from being caught by his brother you weren't’ sure. But what you WERE sure about, was that you were about to have an amazing time.

You hooked Rus’ legs in your arms and angled him slightly. Your cock was still slick from his mouth and you took advantage of that fact to slather it over his opening. Slowly you slid in til the head was inside. Rus groaned, his hands balling your sheets at the feeling of your intrusion. 

“I SAID TO FUCK HIM!” Berry slapped a hand over your ass, making you jolt and push in more. But suddenly his hands were on your ass and pushed you roughly, making you hilt in one go. 

Papyrus yelled out, his hands reaching your thighs to hold on as Berry grabbed your hips and made you move. He pushed and pulled you fast and roughly, making you fuck Papyrus into the mattress.

“THAT’S BETTER...NOW...FOR MY TURN.” 

You turned your head only to see that he held your hips and lined his face to your ass. You gasped as you felt his slimy tongue prodding at your entrance. The thing wriggled and writhed inside of you making you whine and groan, each press of his skull made you thrust into Rus but you pushed back into Sans for more. The rhythm was nearly broken as you felt yourself fast approaching your peak. “F-fuck! I’m...i’m gonna.” 

“DON’T YOU DARE!” Sans barked at you. His hand slapping your ass again, making you yelp. He moved his hand around and grasped at your cock, a ring of crimson magic surrounded the base and you cried out at the tingling prickles it sent up your spine. 

“THERE, NOW ONLY IF YOU’RE A GOOD BOY WILL YOU GET TO CUM. I KNOW HOW WEAK YOU HUMAN MALES ARE. YOU GO ONCE AND THAT’S IT. GAME OVER. BUT WITH THAT IN PLACE, WE’LL BE ABLE TO HAVE PLENTY OF FUN.”

You shuddered as you felt him seat himself behind you while chuckling at your predicament. “I HOPE YOU’RE PREPARED HUMAN. BECAUSE THIS IS GOING TO BE ONE, _BUMPY_ , RIDE.”

Your eyes widened as you felt the head of his cock pressing into you. Wait..was...was it RIBBED?! SHIT!

You cried out as Sans pushed into you slowly, his own grunts and groans sounding from behind. Rus’s long arms snaked around you and grabbed the wings of Berry’s pelvis, pulling him in faster. The feeling of being stretched burned and made tears form in your eyes before a shot of something hot inside of you made the pain recede. “heh...it’s a good thing that monsters are naturally lubricating eh darlin’?” Rus explained away the phenomena and it made you give a sigh of relief. 

“Ffuck...please...just...fuck me Sans...please!” your voice was getting desperate. Your balls ached and every drag and pull of Berry’s cock made you jolt with pleasure. 

“WELL, YOU DID ASK NICELY.” he chuckled before pulling back and slamming into you. This in turn made you slide into Rus’ hot tight hole, the push and pull of the domineering skeleton created a rhythm between the three of you that had you seeing stars. The slap of flesh on bone sounded through the room as you couldn’t help but scream and moan their names as they both wrecked you. 

“Please! Please I need to cum...please I wanna cum so bad!” Your voice cracked from your screaming, making it come out gravely but slightly whining as well. 

Berry laughed menacingly behind you. 

“Not. Yet.”

He pushed you down onto his brother, the other locking his arms around you, holding you tight while Sans repositioned himself and pulled you closer to him. His ribbed and bumped dick made sloppy sounds as it pummeled you relentlessly. You held onto Rus’s ribs for dear life as you pushed back into Berry, trying your best to fuck the taller skeleton that had you pinned. 

Drool dribbled out of your mouth as your tongue hung out of it, your eyes rolled into the back of your head as each thrust in or out sent jolts of electric pleasure through your body, each one like a miniature orgasm in themselves. “Puhleeeheeesssee!” you pleaded, mind going blank. 

Berry growled from behind you. “YOU’VE BEEN SUCH A GOOD BOY, TAKING ALL OF ME, SUCKING ME DEEP INTO YOUR TIGHT LITTLE ASS….” He leaned up next to your ear, pelvis grinding into you and his hand came around to cup your balls. “Cum For Me Human.”

You felt the magic release from your cock and cum you did. Berry thrust into you again, his magic hitting right on your prostate and making you see stars. 

“Yesss….Cum For The Malevolent Sans! Shit...I...I’m Going To Fill You With My Magic...Take It All!” His thrusts became erratic as his hips became a blur, chasing his own release. Rus yelled out beneath you at the feeling of Berry Manhandling the magic on his thighs as he shot off another load of his own burnt orange seed. 

Berry nearly roared his own release as he reached his peak. His fangs sunk deep into the meat of your arm while his hips twitched and thrust, trying to prolong his orgasm. 

You felt your own stomach distend slightly with the amount of cum shooting into you. You collapsed on top of Rus, fully spent as Berry did the same, lying on top of you. His tongue lapped at the blood coming off of your deltoid and nearly purred as the afterglow hit him. 

He rolled off of you, magic dissipating and pulled you into him and out of Rus. Papyrus got to his feet and found a nearby towel to clean up. He offered you a monster candy which you gratefully accepted, still wincing at the feeling of your abused muscles. 

Rus curled around you and Sans, holding you close and pulling the duvet over your naked, sweaty bodies.  
“That was...amazing...thank you…” you said sleepily. 

“well...i hope you can handle two friends with bonefits.” Rus’s sleepy drawl whispered in your ear. You chuckled as Berry groaned at the pun. 

“MUTT!”

“yes m’lord?”

“SHUT UP.”

“yes m’lord.” 

You laughed lightly at the interaction before drifting off to sleep.

**Author's Note:**

> This was actually a request from a Discord server I'm on. It's supposed to be Reader from my one shots having caught 'Rus reading her sketch diary which had tidbits of what she remembered about the AU's and the like seeing she's from beyond the 4th wall and everything. But the guy that requested it asked if I could do a DMAB for him. So...here it is. My gender bent reader oemaki.
> 
> I'll be posting the original here shortly after this goes up so you can see the full one shot that this spawned from.
> 
> If you have requests or prompts please, feel free to shoot me an ask on my Tumblr.  
> https://amashi-zaino.tumblr.com/


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